Raster projection and development of curved surfaces

By fully exploiting the potential of monoscopic techniques, thus confining stereoscopic procedures to irregularly-shaped surfaces, one faciliates the measuring process itself as well as the wider acceptance of photogrammetry in architectural and archaeological documentation. Single-image approaches for 3D surfaces of known analytical expression may lead to products in either vector form via monoplotting or raster form. Besides orthoimaging, in the latter case appropriate cartographic projections have also to be considered according to the needs of the users; for developable surfaces, furthermore, digital “unwrapping ” of the original images is possible, too. These questions of documenting regular surfaces are addressed in the present contribution which has been motivated by the impressive number of tasks falling into this category and, more specifically, by the full photogrammetric documentation of the 13 th-century Byzantine frescoes of the Protaton Church, Mt. Athos. Finally, the approaches are illustrated with examples of raster projections and developments of non-metric imagery of paintings on cylindrical arches of varying diameters and spherical surfaces. 1